visible, the water will now appear to be suspended in the tube without any natural means of support.
The papers are again placed on the ends of the tube, where, being wet, they readily adhere. The hands are now placed one on each end and the tube is reversed; this is necessary to bring the cap with the hole in it to the top. The top paper is then pierced with the hatpin, which, passing through the hole in the cap, gives the impression that there cannot be anything but the paper covering the ends of the tube. When the pin is withdrawn the air rushes into the tube, and, as a natural consequence, the paper and disc fall from the bottom, liberating the water. The bowl should be half full of water when the cap falls, to avoid fracture of the glass. The cap is then brought away from the top of the tube under cover of the piece of paper, and both are dropped into the bowl, when the tube can be once more given for examination.
The Hydrostatic Tumbler.—This trick, which is similar in principle to that immediately preceding it, is preferred by some as being less cumbersome; it is also easier to work and consequently entails less anxiety on the part of the
